<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
            list-style: none;
        }

        ul {
            width: 200px;
            height: 200px;
            border: 1px solid;
            margin: 40px auto;
            perspective: 400px;
        }

        ul li {
            width: 200px;
            height: 200px;
            background-color: red;
            transform: rotateX(45deg);
        }
    </style>
</head>

<body>
    <ul>
        <li></li>
    </ul>
</body>

</html>